Series of exon-skipping events in the elastic spring region of titin as the structural basis for myofibrillar elastic diversity

Alexandra Freiburg, Karoly Trombitas, Wolfgang Hell, Olivier Cazorla, Francoise Fougerousse, Thomas Centner, Bernhard Kolmerer, Christian Witt, Jaques S. Beckmann, Carol C. Gregorio, Henk Granzier, Siegfried Labeit

Research output: Contribution to journalArticlepeer-review

291 Scopus citations


Titins are megadalton-sized filamentous polypeptides of vertebrate striated muscle. The I-band region of titin underlies the myofibrillar passive tension response to stretch. Here, we show how titins with highly diverse I-band structures and elastic properties are expressed from a single gene. The differentially expressed tandem-Ig, PEVK, and N2B spring elements of titin are coded by 158 exons, which are contained within a 106-kb genomic segment and are all subject to tissue-specific skipping events. In ventricular heart muscle, exons 101 kb apart are joined, leading to the exclusion of 155 exons and the expression of a 2.97-MDa cardiac titin N2B isoform. The atria of mammalian hearts also express larger titins by the exclusion of 90 to 100 exons (cardiac N2BA titin with 3.3 MDa). In the soleus and psoas skeletal muscles, different exon-skipping pathways produce titin transcripts that code for 3.7- and 3.35-MDa titin isoforms, respectively. Mechanical and structural studies indicate that the exon-skipping pathways modulate the fractional extensions of the tandem Ig and PEVK segments, thereby influencing myofibrillar elasticity. Within the mammalian heart, expression of different levels of N2B and N2BA titins likely contributes to the elastic diversity of atrial and ventricular myofibrils.

Original languageEnglish (US)
Pages (from-to)1114-1121
Number of pages8
JournalCirculation research
Issue number11
StatePublished - Jun 9 2000


  • Atrium
  • Diastole
  • Elasticity
  • Titin

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine


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